The first practical mailers as a type of business form appeared in the 1960's with the advent of the type of form illustrated in U.S. Pat. No. 3,104,799, issued to D. J. Steidinger. That particular type of business form included a prestuffed, sealed envelope assembly wherein interior plies could be imaged with variable information through the use of interior image transfer systems such as interleaved carbon, hot spot carbon, mated front, coated back type systems, etc. The mailers were in continuous form and thus ideally suited to being imaged on computer operated printers. The mailers were utilized for a large variety of purposes. For example, they were commonly used by educational institutions to mail grade reports to students. In this type of usage, there was no need for a return envelope.
Conversely, many businesses employed this type of mailer to invoice customers. In this case, the customer was expected to return payment of the invoice and to facilitate that, the mailer included a return envelope.
As a result of the arrival of mailers of this sort on the scene, a whole new segment of the business forms industry developed. Specifically, the same developed to provide a large variety of different types of mailers as business forms that could be utilized to meet the needs of any of a variety of businesses. As part of this evolution, new business forms processing equipment for processing the mailers also were developed. Whereas the mailers of the type illustrated in the previously identified Steidinger patent were commonly manufactured in the manufacturing plants of the large business forms manufacturers, certain types of the newly developed equipment were intended for use by the user of the business form, which is to say that they were intended to be located at the place of business of the user of the business form and operated by the user's employees just as deleavers, bursters, trimmers and the like had been operated for many years.
This type of equipment has been referred to as glue folders. The equipment is particularly adapted to apply glue either to individual sheets of paper that are to be folded by the machine into an envelope or mailer or, in some cases, to individual form lengths of a continuous ply for the same purpose.
To facilitate handling of the sheets or ply, it is generally desirable that glue be placed by the machine on a single side of the sheet or ply of the paper. In this way, the opposite side remains free from glue and thus serves as a side by which the form may be supported during the processing thereof without concern for the form hanging up in the processing equipment as a result of contact between the glue and the processing equipment. This factor, in turn, has not made it particularly easy to provide a large variety of mailers that may be processed on such equipment and which meet the regulations of the United States Postal Service, requiring that such mailers be sealed on all sides. The difficulty of producing such a form becomes all the more acute when the mailer is intended to have a return envelope.
The present invention is directed to overcoming the above difficulty.